Make all libraries Multi-Arch: same

[smcv]

I've recently been experimenting with building a Flatpak runtime from the Steam Runtime packages (#54) so that it can be used to run the Steam client as a Flatpak app. Because the Steam client and some games are 32-bit-only, but some other games are 64-bit-only, the 64-bit version will need to be run in a runtime with multilib (lib, lib64) or multiarch (lib/i386-linux-gnu, lib/x86_64-linux-gnu) so that all game-related libraries can be parallel-installed in both 32- and 64-bit versions.

At the moment, the Steam Runtime uses separate amd64/ and i386/ pseudo-chroots and enables them with LD_LIBRARY_PATH, but that's a bit of a hack: they both contain identical etc/ and include/, and nearly-identical usr/share/, differing only in non-functional files in usr/share/doc/.

No libraries in the Steam Runtime write directly to lib (which would collide between architectures), only to lib/*-linux-gnu. There are only a few libraries that write to usr/lib and not usr/lib/*-linux-gnu, namely:

• libappindicator
• libindicator
• libvpx
• network-manager
• tbb

So patching those 5 libraries is sufficient to make everything multi-arch-friendly, such that all the relevant libraries for both amd64 and i386 can be installed in a single chroot.

All of those libraries were subsequently made multi-arch-friendly in Debian and Ubuntu, so all that's needed here is to backport the relevant changes.

This change would also make it possible for the Steam client itself to merge amd64/ and i386/ into a single pseudo-chroot, but I have not tested this. nvidia-cg-toolkit would have to be excluded (#77) or installed for only one of the two architectures. Similarly, zenity would have to be installed for only one of the two architectures, presumably i386 for widest applicability - or just omitted, because the Steam client depends on the host system to provide zenity anyway?

[smcv]

Here are dget'able source packages which implement this:

• https://people.collabora.com/~smcv/expires-201710/libappindicator_0.4.92-0ubuntu1.1%2bsteamrt1.dsc
• https://people.collabora.com/~smcv/expires-201710/libindicator_0.5.0-0ubuntu1%2bsteamrt1.dsc
• https://people.collabora.com/~smcv/expires-201710/libvpx_1.0.0-2.dsc
• https://people.collabora.com/~smcv/expires-201710/network-manager_0.9.4.0-0ubuntu4.2%2bsteamrt2.dsc
• https://people.collabora.com/~smcv/expires-201710/tbb_4.0+r233-1+steamrt1.dsc (needs fixing)

libvpx is a slightly newer version from Debian; the others are backports.

Diffs since previous versions of the relevant packages for review (cc @fledermaus):

• https://people.collabora.com/~smcv/expires-201710/libappindicator_0.4.92-0ubuntu1.1%2bsteamrt1.diff.txt
• https://people.collabora.com/~smcv/expires-201710/libindicator_0.5.0-0ubuntu1%2bsteamrt1.diff.txt
• https://people.collabora.com/~smcv/expires-201710/libvpx_1.0.0-2.diff.txt
• https://people.collabora.com/~smcv/expires-201710/network-manager_0.9.4.0-0ubuntu4.2%2bsteamrt2.diff.txt
• https://people.collabora.com/~smcv/expires-201710/tbb_4.0+r233-1%2bsteamrt1.diff.txt

[smcv]

There's one more to do: libvulkan1 also needs multiarchifying.

[smcv]

• https://people.collabora.com/~smcv/expires-201710/tbb_4.0%2br233-1%2bsteamrt2.dsc
• https://people.collabora.com/~smcv/expires-201710/vulkan_1.0.8.0%2bdfsg1-0ubuntu1%2bsteamrt2.dsc

Debdiffs:

• https://people.collabora.com/~smcv/expires-201710/tbb_4.0+r233-1%2bsteamrt2.diff.txt
• https://people.collabora.com/~smcv/expires-201710/vulkan_1.0.8.0%2bdfsg1-0ubuntu1%2bsteamrt2.diff.txt

[fledermaus]

These seem reasonable - the gir files are not coinstallable but as discussed offline we don't need them to be, so that should be fine.

[smcv]

All these packages have been fixed in OBS, and should be in the next push to the public apt repositories.